1. Field of the Invention
The present invention relates to a modified glucose dehydrogenase (GDH) with improved substrate specificity and/or thermal stability, and more specifically to a modified PQQ-dependent glucose dehydrogenase (PQQGDH) having pyrroloquinoline quinone (PQQ) as the coenzyme, and to a manufacturing method and a glucose sensor.
The modified PQQGDH of the present invention is useful for measuring glucose in clinical assay, food analysis and the like
2. Description of the Related Art
PQQGDH is a glucose dehydrogenase having pyrroloquinoline quinone (PQQ) as its coenzyme. Because PQQGDH catalyzes a reaction in which glucose is oxidized to produce gLuconolactone, it can be used in measuring blood sugar. Blood glucose concentration is extremely important in clinical diagnosis as a marker of diabetes. at present, the principal method of measuring blood glucose employs a biosensor using glucose oxidase, but the reaction is affected by dissolved oxygen concentration, raising the possibility of errors in the measurements. attention has focused on PQQ-dependent glucose dehydrogenase as a substitute for glucose oxidase Our group discovered that the NCIMB 11517 strain of Acinetobacter baumannii Produces PQQ-dependent glucose dehydrogenase, conducted gene cloning and constructed a high-expression system (Japanese Patent Application Laid-Open No. H11-243949). Compared with glucose oxidase, PQQ-dependent glucose dehydrogenase had problems in substrate specificity and thermal stability.
An object of the present invention is to provide a PQQGDH with improved substrate specificity and/or thermal stability.